1. Field of the Invention
This invention pertains in general to determining recommendations through collaborative filtering and related techniques and in particular to identifying relationships used to determine the recommendations by tracking interactions across multiple web sites.
2. Description of the Related Art
Many commercial web sites desire “stickiness.” That is, the sites want people browsing the sites to stay on the sites for a long time. For example, a media site that generates revenue through advertising wants a person to view many articles and other content, so that the site will have more opportunities to present advertisements. Likewise, a retail site that sells merchandise wants a person to stay on the site longer in order to increase the number of the person's purchases.
One way to increase stickiness is by observing a person's behaviors and presenting the person with a list of suggestions that might be of interest. If a person reads a news story about a particular subject, the site presents a list of other stories that he might also want to read. Similarly, if the person buys a particular item, the site presents a list of related items she might also wish to purchase. For example, if the person browses the web page of a camera on the site, the site will present her with a list of suggested accessories, such as memory cards, carrying cases, etc.
Web sites use collaborative filtering techniques to detect relationships and generate suggestions. Generally speaking, collaborative filtering is based on a collection of relationships obtained by monitoring the behaviors of people. When a person expresses a relationship by, e.g., browsing a web page for a certain type of camera or reading a news story on a certain topic, collaborative filtering analyzes the collection to identify people who expressed the same relationship, and then calculates a set of recommendations based on the other relationships expressed by the identified people. Thus, if many people who browse a web page for a camera also browse a web page for a certain memory card, the web page for that card can be presented as a suggestion to a person who initially browses the camera page.
The recommendations produced through collaborative filtering improve as the amount of relationships in the collection increases. Likewise, the recommendations improve as more is known about the person for whom the recommendations is being made. Since improved recommendations lead to improved stickiness and other desirable effects, web site operators would like to perform collaborative filtering based on the broadest possible set of relationship data.
However, most web sites that perform collaborative filtering base their recommendations on only a limited set of relationship data. There is no convenient way for a site to track a person's interactions (and expressed relationships) across other web sites. Accordingly, a site must base its recommendations on only the behaviors it directly observes. Therefore, less is known about the person for whom the recommendations are made, and the pool of relationship data on which the collaborative filtering is based is also smaller. The recommendations are of lower quality as a result.
Moreover, the relationship data used for collaborative filtering are not heterogeneous in type. The relationship data may associate different types of news stories, or different consumer goods, but the data do not associate completely heterogeneous items, such as consumer goods and newsgroups, news stories and images, or people and events. This deficiency leads to homogenous recommendations that may be of less value to web sites.
As a result, there is a need in the art for a way of gathering relationship data and producing recommendations that does not suffer from the problems described above.